Support-facet-mediated metal-support interaction regulation of Pt-based catalyst for efficient dehydrogenation

Methylcyclohexane (MCH) / toluene (TOL) system is considered as a promising candidate for large-scale green hydrogen storage, and the catalytic MCH dehydrogenation is the key reaction for the effective system recycling. As the important property, the electronic structure of Pt active sites determines the dehydrogenation dynamics, but the mechanism for its effect on dehydrogenation is still ambiguous. Herein, we proposed a support (CeO2) facet mediated method to rationally regulate metal-support interaction as well as d-orbital electron occupation of Pt sites for efficient MCH dehydrogenation. The characterizations indicate the interfacial Pt-O coordination numbers are reduced from Pt/CeO2 (110) to Pt/CeO2 (111) and Pt/CeO2 (100), leading to the gradually decreased interfacial charge transfer and metal-support interaction (MSI). The in-situ characterization of catalytic reactions and DFT calculation results confirm the rate-limiting step of dehydrogenation is the desorption of products H2 and TOL. The MCH dehydrogenation performances show the catalytic activities of Pt/CeO2 (111) > Pt/CeO2 (110) > Pt/CeO2 (100). Notably, Pt/CeO2 (111) with moderate MSI induces a moderate eg-orbital electron occupation of Pt-O-Ce sites to accelerate H2 formation and desorption, while the resulted least t2g-orbital electron occupation of Pt-Pt sites weakens TOL adsorption, therefore showing the best TOL yield of 91.2% at 350 °C and WHSV of 4.62 h-1. This work reveals the mechanism of support-facet-mediated d-orbital electron occupation regulation of Pt sites, which provides a guidance for the rational design of highly efficient dehydrogenation catalysts.